Porous supramolecular gels produced by reversible self-gelation of ruthenium-based metal-organic polyhedra

Supramolecular gels based on metal-organic polyhedra (MOPs) represent a versatile platform to access processable soft materials with controlled porosity. Herein, we report a self-gelation approach that allows the reversible assembly of a novel Ru-based MOP in the form of colloidal gels. The presence of cationic mixed-valence [Ru2(COO)4]+ paddlewheel units allows for modification of the MOP charge via acid/base treatment, and therefore, its solubility. This feature enables control over supramolecular interactions, making it possible to reversibly force MOP aggregation to form nanoparticles, which further assemble to form a colloidal gel network. The gelation process was thoroughly investigated by time-resolved zeta-potential, pH, and dynamic light scattering measurements. This strategy leads to the evolution of hierarchically porous aerogel from individual MOP molecules without using any additional component. Furthermore, we demonstrate that the simplicity of this method can be exploited for the obtention of MOP-based gels through a one-pot synthetic approach starting from MOP precursors. Our study demonstrates how the charge manipulation of metal-organic polyhedra (MOPs) provides a viable route for their assembly into supramolecular gels and porous aerogels, eliminating the need for supplementary components.

Automated summary

This study presents a self-gelation approach based on metal-organic polyhedra (MOPs) that allows for the reversible assembly into nanoparticles and colloidal gels through charge manipulation. Furthermore, the simplicity of this method is demonstrated by synthesizing MOP-based gels via a one-pot synthetic approach. The research highlights the potential application of charge manipulation in the formation of supramolecular gels and porous aerogels based on MOPs.